Dynamoelectric machine utilizing pre-formed winding connectors and method of making

ABSTRACT

Series connections of rectangular aluminum multi-strand coil leads of a dynamoelectric machine can be readily made in a confined space by the utilization of prefabricated aluminum connectors having apertures therein to snugly receive the uninsulated extremities of the coil leads being joined. In making the weld, the individual strands forming the coil leads initially are joined e.g., utilizing MIG-welding or other conventional joining techniques, whereafter the joined strands are welded to the connector side wall and the weld is finished with a concave aluminum button to maximize the reliability of the joint. A suitable electrical insulation then is applied over both the connector and the uninsulated extremities of the coil leads and the joined leads are mechanically secured to the motor end turns to reduce stress upon the joint during motor operation. Prefabricated connectors also are disclosed for joining the phase and/or series leads to the arcuately shaped ring conductor without canting the natural curvature of the conductors forming the connection.

United States Patent 1151 3,675,058 Beddows et a1. July 4, 1972 [541DYNAMOELECTRIC MACHINE 2,403,642 7/1946 Draxler .310/71 UTILIZINGPRE-FORMEI) WIN G 3,112,564 12/1963 Murray ..29/470.5 CONNECTORS ANDMETHOD F FOREIGN PATENTS OR APPLlCATlONS MAKING 508,875 7/1939 GreatBritain ..310/201 [72] Inventors: Norman A. Beddows; John A. Quigley,

both of Scotia; Warren P. Wielt, Schenectady, all ofN.Y.

[73] Assignee: General Electric Company [22] Filed: Sept. 8, 1970 [21]App1.No.: 70,165

[52] US. Cl ..310/71, 174/84, 310/201 [51] Int. Cl. ..ll02k 11/00 [58]Field of Search ..310/179, 71, 270, 271, 260,

[56] References Cited UNITED STATES PATENTS R24,074 10/1955 Buchanan..174/74 A 1,171,591 2/1916 Chubb ..174/84 1,403,185 1/1922 Mix ..310/71X 2,407,935 9/1946 Perfetti et a1.. ..310/201 3,192,423 6/1965 Pearson..174/94 X 3,243,501 3/1966 Patrick et al... .....174/94 X 3,461,2218/1969 Herb 174/84 3,426,227 2/1969 Miller et al..... ....310/50 X3,020,333 2/1962 Bangert et al ..29/470.5 X

Primary Examiner-Lewis H. Myers Assistant Examiner-U. WeldonAtlorneylohn J. Kissane, James C. Davis, Jr., Frank L. Neuhauser, OscarB. Waddell and Joseph B. Forman [57] ABSTRACT Series connections ofrectangular aluminum multi-strand coil leads of a dynamoelectric machinecan be readily made in a confined space by the utilization ofprefabricated aluminum connectors having apertures therein to snuglyreceive the uninsulated extremities of the coil leads being joined. lnmaking the weld, the individual strands forming the coil leads initiallyare joined e.g., utilizing MIG-welding or other conventional joiningtechniques, whereafter the joined strands are welded to the connectorside wall and the weld is finished with a concave aluminum button tomaximize the reliability of the joint. A suitable electrical insulationthen is applied over both the connector and the uninsulated extremitiesof the coil leads and the joined leads are mechanically secured to themotor end turns to reduce stress upon the joint during motor operation.Prefabricated connectors also are disclosed for joining the phase and/orseries leads to the arcuately shaped ring conductor without canting thenatural curvature of the conductors forming the connection.

4 Claims, 3 Drawing Figures PA'TENTEDJUL 4:972 3,575,058

zen/V F G. 3 INVENTORS NORMAN A. BEDDOWS JOHN A. QUIGLEY WARREN P. WIELTTHEIR ATTORNEY DYNAMOELECTRIC MACHINE UTILIZING PRE- FORMED WINDINGCONNECTORS AND METHOD'OF MAKING This invention relates to an improvedmethod of forming series and/or phase connections within adynamoelectric machine and to machines thus formed. In a more particularaspect, this invention relates to the use of prefabricated aluminumconnectors to permit electrical joining of multi-strand rectangularaluminum coil leads within confined areas of a dynamoelectric machine.

In the fabrication of dynarnoelectric machines, it is often necessary toform series and phase connections for a r'nultitude of prewound coils toproduce the desired machine winding. While these connections can easilybe brazed when the conductors forming the coils are copper, in manymotor applications aluminum conductors are desirable to minimize saltaccumulation, or dendritic growth, and conductor corrosion. For example,motors employed for circulating reactant gases at high pressure duringammonia synthesis typically operate in an environment which may containas much as 13 percent liquid ammonia at a temperature of approximately100 F and a pressure of about 5,000 lbs/sq. in. Motors for suchapplications must be wound with aluminum coils to achieve anyappreciable motor life expectancy during sustained recirculation ofammonia! gases. Series connections of aluminum coil leads, however, areinhibited not only by the difficulties inherent in joining aluminumconductors but also by the confined space wherein the joint must bemade. Moreover, because the motor coils often employ fluorocarbonpolymeric insulating coating to inhibit corrosion of the underlyingcoils, prolonged heating of the coil leads during formation of the jointcan tend to decompose the polymer releasing toxic gases and degrade theinsulation in the affected area beyond use.

Among the techniques heretofore proposed to form the series and phaseconnections of aluminum coils for ammonia synthesis motors is to shapethe leads to be joined into a confronting attitude whereafter the leadsare M.I.G. welded (i.e., welded utilizing a consumable electrode in aninert atmosphere) employing a reusable copper mold disposed below thejoint both to retain the liquid aluminum produced during welding and toform a heat sink tending to inhibit decomposition of the coil insulator.After welding, the copper mold is removed and the joint is suitablyinsulated, e.g., utilin'ng techniques disclosed in N.A. Beddows US.patent, Ser. No. 3,488,537, assigned to the assignee to the presentinvention. Although welding of multi-strand aluminum coil leadsutilizing a removable mold produces a highly reliable connection,extensive set-up time is necessary to properly shape the aluminumconductors into a confronting attitude within the reusable mold and thespace required for manipulating the mold necessarily produces a bulkyconnection. Moreover, because the insulation must be stripped from thecoil leads over a considerable span, e.g., approximately 6 inches, toassure proper positioning of the shaped leads within the mold whileproviding an adequate span between the insulator and the mold,considerable time is required to re-insulate the welded connection.

It also has been suggested that the series and phase leads be brazedemploying a fluoride flux and an aluminum alloy filler between theoverlapped strands of the leads being joined. The joint formed bybrazing, however, often is skewed inhibiting subsequent electricalinsulation of the joint. The corrosive nature of the fluoride flux alsorequires water washing of residual flux from the joint tending tocontarriinate adjacent motor components and inhibit the formation of adense insulation structure.

It is therefore an object of this invention to provide a novel method ofrapidly forming reliable motor winding connections within a confinedarea.

It is also an object of this invention to provide a method of formingmotor winding connections wherein the leads being joined do not requiresubstantial shaping from the normal curvature of the leads.

It is a further object of this invention to provide a method of formingmotor winding connections wherein minimal stripping of the leadinsulation is required prior to joining.

It is a still further object of this invention to provide adynamoelectric machine wherein reliable motor winding connections areproduced within a confined area.

These and other objects of this invention generally are achieved by theutilization of a prefabricated connector having diverse slots therein tosnugly receive the uninsulated extrernities of the rectangular leadsbeing joined. The leads then are electrically and mechanically joined tothe connector, e. g. by any conventional aluminum joining technique suchas M.I.G. or T.I.G. welding or brazing, whereafter both the connectorand uninsulated extremities of the leads are insulated prior to beingsecured into position within the machine. Thus, a dynamoelectric machinein accordance with this invention would include a plurality of coilseach formed of at least one rectangular conductor wound in apre-determined configuration and positioned within slots in stackedmagnetic laminations at an attitude such that the coil leads protrudeoutwardly from one end of the magnetic larninations. Series and phaseconnections electrically joining the coil leads to form the machinewinding are made utilizing prefabricated electrically conductiveconnectors having a plurality of diverse slots therein to respectivelyreceive the extremities of pre-determined leads to be interconnected.Each of the lead extremities within the connector are welded to theconnector sidewall and an insulating coating is provided atop both theconnector and the uninsulated lead extremities prior to mechanicallysecuring the connected leads within the motor.

While the novel features of this invention are particularly pointed outand distinctly claimed in the appended claims, a more completeunderstanding of the basic principles of this invention may be obtainedfrom the following detailed descrip tion taken in conjunction with theaccompanying figures wherein:

FIG. 1 is a broken away sectional view illustrating diverse statorwinding connections formed in accordance with this in vention,

FIG. 2 is a partially exposed isometric view of a prefabricatedconnector suitable for forming series connections of the stator coilsand,

FIG. 3 is an isometric view illustrating a prefabricated connectorsuitable for joining orthogonally disposed motor leads.

The end turn cavity 10 of a wye wound dynarnoelectric machine stator 12connected in accordance with this invention is illustrated in FIG. 1 andgenerally includes prefabricated aluminum connectors 14 and 16 forserially interconnecting the aluminum coil leads of the diverse coilsforming the stator and for joining the aluminum phase conductors withthe aluminum circuit ring conductors of the motor, respectively. Exceptfor the use of prefabricated connectors to electrically join selectivecoil leads, stator 12 is otherwise conventional in design being formedby the disposition of pre-wound insulated coils 18 within aligned slotsin stacked magnetic larninations 20 with only the coil end turns 22 andleads 24 protruding from the stacked larninations being illustrated inFIG. 1. Coil 18 typically is formed of a plurality (three in theillustrated Figure) of juxtaposed rectangular aluminum strands woundinto a predetermined configuration and wrapped with a plurality oflayers of fluorocarbon polymeric tapes 26 in accordance with theteachings of the heretofore cited Beddows US. patent, Ser. No.3,488,537. In conventional fashion, a housing 28 serves to support thestacked stator larninations and extends as a shroud over the end turncavity to shield the windings from injury. While motor 10 is describedas a wye wound dynamoelectric machine because the novel features of theinvention are particularly suited to such type machine windings, theprefabricated connectors of this invention can be utilized with anymotor winding configuration, if desired.

Prefabricated connector 14 designed for serially interconnecting thealuminum coil leads within the motor is illustrated more clearly in FIG.2 and generally comprises a rectangular,

high melting point aluminum body having two vertically displacedparallel apertures 30 extending completely through the connector. Eachof apertures 30 is rectangular in configuration and dimensioned relativeto the rectangular strands forming coils 18 to snugly receive the coilleads within the apertures. in general, the lateral dimensions ofapertures 30 should not exceed the lateral dimensions of the coil leadsbeing inserted therein by more than 20 mils in either direction with a5-8 mil oversize of the apertures relative to the rectangular conductorshaving been found optimum to snugly receive the coil leads withoutproducing undue difficulty during insertion. If desired, insertion ofthe coil leads into the connector can be eased by rounding the edges ofthe leads and/or by the application of a suitable aluminum lubricant tothe leads. Preferably the center to center span between rectangularapertures 30 is approximately equal to the span between the coil leadsbeing connected to avoid undue shaping of the coil leads tending tospread the laminar strands and making difficult the insertion of thecoil leads into the connectors.

To reduce the bulk of the connection, connector 14 desirably is made tobe as small as possible while assuring a mechanically and electricallysecure joint between the joined coil leads. To achieve this end,peripheral lips 32 protruding in the direction of the coil leads can beprovided to strengthen the joint without unduly increasing the bulk ofthe connector or a portion of the intermediate portion of the connectorsituated between apertures 30 can be removed to reduce the weight of theconnector. In general, 0.5 X 0.54 inch rectangularly shaped aluminumconnectors having two 0.35 X 0.25 inch slots separated by a center pieceof 1.34 inch have been found suitable for joining coil leads formed ofthree laminar 0.260 X 1.10 aluminum conductors. An insertion depth ofapproximately 0.45 inch is used to assure a deep reliable joint to theconnector sidewall while providing a cavity to receive aluminum weldmentmaximizing the reliability of the connections (as will be more fullyexplained hereinafter).

To form the end turn connections of aluminum coils 18 in accordance withthis invention, fluorocarbon polymeric tapes 24 are stripped from theends of the coil leads to a distance of approximately 1.95 inch toprovide a span of approximately l k inch from the connector to thepolymeric adjacent tapes. Connector 14 then is juxtaposed with thestripped coil leads and the leads are inserted within apertures 30 toterminate slightly short of the connector face remote from the coil.Because the span between the apertures of the connector is approximatelyequal to the span between the coil leads being joined, the apertures liesubstantially within the plane of the coil leads and relatively noshaping of the coil leads is required. The connector and insulating tapeproximate the connector then are wrapped with wet asbestos to inhibitthermal degradation of the fluorocarbon polymeric tapes and joining iscommenced by initially welding together the individual strands formingeach coil lead, e.g., utilizing conventional M .l.G. welding techniqueswith a welding power of 150 amps and 12 volts ac, whereafter the joinedstrands are M.I.G. welded to the sidewalls of the connector in anidentical fashion. By terminating the coil leads short of the connectorface remote from the coil, a deeper weld within the connector isattained relative to welds effected when the coil leads completely fillthe connector aperture. To avoid decomposition of the fluorocarbonpolymeric tapes wound about the coil, the arc interval during weldingpreferably should not exceed approximately 30 seconds for a 0.26 X 1.1aluminum conductor.

After welding the coil leads to the connector sidewall, aluminumweldmetel is deposited atop the coil lead end to form a concave button36 further insuring the integrity of the joint. The joint then is filedsmooth and insulated in accordance with the teachings of the priormentioned Beddows patent by wrapping both the connector and uninsulatedextremities of the leads with a fusible fluorocarbon polymeric tape,e.g., a polyfluoroethylene-perfluoropropylene copolymer, whereafter acomposite tape consisting of a fusible fluorocarbon polymer having aninfusible fluorocarbon polymeric coating, e.g. a coating ofpolytetrafluoroethylene, is wrapped thereon with the fusiblefluorocarbon polymeric tapes of the two tapered layers being in contact.The tapes then are induction-melted to form a liquid imperviousinsulation and the insulation is over taped with Mica-mat and glass tapewhereafter vacuum pressure impregnation of the tapes with an epoxy resinand subsequent curing of the resin produces a mechanical armor for theconnection.

Series connections of the coil end turns also can be achieved when thecoil leads extend completely through the connector to protrude a slightdistance, typically less than one-fourth inch, from the face of theconnector remote from the coil. T.I.G. welding (i.e. welding with anon-consumable electrode in an inert atmosphere) then preferably isemployed to join the strands and weld the joined strands to theconnector sidewall. Welding with the coil lead ends protruding from theconnector, however, does not produce a deep weld within the connectionand therefore, this technique is not preferred for forming highlyreliable welds.

It will be appreciated from the foregoing that reliable seriesconnections of multiple strand aluminum coils can be made within aconfined space by the use of aluminum prefabricated connectors.Moreover, because the connectors are designed with apertures situatedapproximately within the normal plane of the coil leads being connected,relatively little shaping of the coil leads is required.

FIG. 3 illustrates connector 16 of this invention, which connector isspecially designed to join rectangular aluminum leads disposed insubstantially orthogonal directions, e.g., for connecting the phase orthe series leads to the circuit ring conductor of a conventional wyewound stator. The connector is characterized by slots 38 at oppositeends of the connector to receive circuit ring conductors 40 extendingthrough the upper face of the connector partly into the connector bodywithout requiring the application of axial force to the circuit ringconductors. Similarly, slots 42 disposed along the axial length of theconnector extend through two orthogonal faces of the connector tosuitably receive phase conductors 44 therein. Desirably, the slotsextend to a depth producing a flush fit of the circuit ring and phaseconductors at the slot surface with spans between one-fourth andthree-fourths the connector depth normally being required for amechanically secure joint. To assure superior contact between theconductors and the connector, the end faces of the conductors taper backfrom the confronting slot edge with proximity to the connector surfaceto produce a J weldment 46 during subsequent MiG. welding of theconductors to the connector. As previously described relative to weldingthe series connections, the individual rectangular strands forming thelaminar phase and circuit ring conductors are initially welded. Thejoined conductors then are welded to the connector body and the voidsbetween the sloped end of the conductors and the vertical interior edgesof the slots are filled with aluminum weld to produce an overlyingconcave aluminum button.

While the connector of FIG. 3 is illustrated as having dual center slotsextending through two orthogonal faces of the connector to receive thephase conductors therein, the connector also can be formed utilizing asingle through slot, or aperture, (not shown) situated within the planeof the phase conductors and extending through opposite faces of theconnector. The phase conductors then would be initially inserted intothe center aperture whereafter the ring conductors could be dropped intoslots cut into orthogonal faces at opposite ends of the connector.

It will be appreciated that the use of prefabricated aluminum connectorsto join rectangular aluminum conductors of a dynamoelectric machinewinding pennits forming of small joints within a confined area withoutthe use of corrosive flux Patent of the United States is:

l. A dynamoelectric machine comprising:

a. a multitude of coils each formed of a plurality of rectangularconductors wound in a pre-determined configuration,

a plurality of stacked magnetic laminations having slots therein forreceiving said coils with the end turns and leads of said coilsprotruding outwardly from at least one end of said magnetic laminations,

, electrical insulation covering each of said coils,

. series and phase connections selectively electrically joining saidcoil leads to provide a machine winding, at least one of saidconnections being characterized by an electrically conductiveprefabricated connected situated at said one end of said stackedlaminations, said prefabricated connector having a plurality of diverseslots therein receiving the uninsulated extremities of the coil leadsbeing joined with each of said lead extremities within said connectorbeing joined to said connector, at least one slot being disposed at eachopposite end of said connector to receive ring conductors therein, saidend slots extending through two orthogonally disposed surfaces of saidconnector, said connector further having at least one additional slotdisposed intermediate said end slots to receive a rectangular conductorextending in a direction substantially orthogonal to the direction ofsaid ring conductors, said connector lying substantially in the plane ofeach of said conductor, and, I

e. an insulating coating atop said connector and said uninsulated coillead extremities.

2. A dynamoelectric machine according to claim 1 wherein said connectorand conductors are aluminum, the upper surface of said lead extremitiesterminates short of the ends of their respective slots, and weld metalfills the remainder of said slots to form concave buttons thereover.

3. A dynamoelectric machine according to claim 2 wherein said connectoris rectangular and each of said slots extend through two orthogonallydisposed surfaces of said connector.

4. A dynarnoelectric machine according to claim 2 wherein said connectorhas two slots disposed intermediate said end slots.

1. A dynamoelectric machine comprising: a. a multitude of coils eachformed of a plurality of rectangular conductors wound in apre-determined configuration, b. a plurality of stacked magneticlaminations having slots therein for receiving said coils with the endturns and leads of said coils protruding outwardly from at least one endof said magnetic laminations, c. electrical insulation covering each ofsaid coils, d. series and phase connections selectively electricallyjoining said coil leads to provide a machine winding, at least one ofsaid connections being characterized by an electrically conductiveprefabricated connected situAted at said one end of said stackedlaminations, said prefabricated connector having a plurality of diverseslots therein receiving the uninsulated extremities of the coil leadsbeing joined with each of said lead extremities within said connectorbeing joined to said connector, at least one slot being disposed at eachopposite end of said connector to receive ring conductors therein, saidend slots extending through two orthogonally disposed surfaces of saidconnector, said connector further having at least one additional slotdisposed intermediate said end slots to receive a rectangular conductorextending in a direction substantially orthogonal to the direction ofsaid ring conductors, said connector lying substantially in the plane ofeach of said conductor, and, e. an insulating coating atop saidconnector and said uninsulated coil lead extremities.
 2. Adynamoelectric machine according to claim 1 wherein said connector andconductors are aluminum, the upper surface of said lead extremitiesterminates short of the ends of their respective slots, and weld metalfills the remainder of said slots to form concave buttons thereover. 3.A dynamoelectric machine according to claim 2 wherein said connector isrectangular and each of said slots extend through two orthogonallydisposed surfaces of said connector.
 4. A dynamoelectric machineaccording to claim 2 wherein said connector has two slots disposedintermediate said end slots.